# Cyrus IMAP Server FAQ

- Using PAM Under Linux when using PAM and shadow passwords, /etc/shadow needs to be readable by the Cyrus user.
- Using NFS We don't recommend it. If you want to do it, it may possibly work but you may also lose your email or have corrupted `cyrus.*` files. You can look at the mailing list archives for more information.
- Virtual hosting - We don't support it and don't plan to support it unless we get a set of complete patches. If you want it, you'll need to do it yourself or use a commercial product. Check the list archives for more information.
- dots in userids - no you can't have a '.' in your username.
- renaming users - nope, not supported.
- plus addressing
- Performance/Capacity/Scaling - There is no good answer for this. It depends on your hardware, your operating system, and how your users use the system. In general, an `imapd` process takes up anywhere from 256 Kbytes of memory to 512 Kbytes when it is first fired up. CPU has not been a big deal, but it may become more important as the imap sessions are encrypted and now that searching may be more frequent. Disk I/O is probably the most important and having a hardware RAID subsystem with an amount of write-back cache would be a good thing.

  Finally, if you are talking about less than 100 interactive users it is likely that any relatively modern hardware can support it. If you are talking about having more than 1000 interactive users, you should know how to predict your utilization, go overboard on hardware, be willing to suffer growing pains, or be able to hire someone that can help.

  There are a number of good performance tuning articles out for Solaris by Adrian Cockcroft. Go to your favorite search engine and look for his name.

## Troubleshooting

Q: I'm getting syslog'd messages from the master process saying processes are "signaled to death by 10". What's up?

  A: If you're using Berkeley DB 3.0.55, try installing some patches to Berkeley DB available from http://www.sleepycat.com/update/3.0.55/patch.3.0.55.html.

Q: I've used `saslpasswd` to create CRAM-MD5 secrets, but imapd doesn't say `AUTH=CRAM-MD5`. Why?

  A: Make sure `/etc/sasldb` is readable by the Cyrus user.

Q: I'm getting messages like:

    Jan 14 13:46:24 grant ctl_deliver[9060]: duplicate_prune: opening
    /var/imap/deliverdb/deliver-x.db: No such file or directory
    Jan 14 13:46:24 grant ctl_deliver[9060]: duplicate_prune: opening
      /var/imap/deliverdb/deliver-y.db: No such file or directory
    Jan 14 13:46:24 grant ctl_deliver[9060]: duplicate_prune: opening
      /var/imap/deliverdb/deliver-z.db: No such file or directory

in my `cyrus.log` file. What's wrong?

  A: These messages are normal; one file is maintained for each user beginning with "x", "y", "z", etc. If you're first starting or you have no users beginning with these letters, these messages are completely normal and can be ignored.

last modified: $Date: 2001/01/31 18:41:34 $
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